The present invention relates to the addition of adhesion promoting additives to ethylene-propylene-nonconjugated diene (EPDM) elastomers.
Adhesion of EPDM elastomers to fibers or fabrics has been very difficult for those skilled in the art. Among the methods used for improving such adhesion are pretreating the fabric with a special latex or a chemically reactive substance, chemically modifying the elastomer, and adding an ingredient directly to an elastomer composition that will render it more adherent upon curing the composition onto a fabric substrate.
Various adhesion promoting additives useful in the last method are disclosed in Belgian Pat. No. 778,284, U.S.S.R. Pat. No. 275,372, French Pat. No. 1,439,245, Rumanian Pat. No. 192,329, and U.S. Pat. No. 2,844,502.
It has been found that an acid of the formula A--COOH).sub.x, or an anhydride thereof, wherein x and A are as defined below, renders ethylene-propylene-nonconjugated diene (EPDM) elastomers more adherent to fibers that have been treated with a resorcinolformaldehyde-latex (RFL) dip when said elastomers are cured directly onto said fibers.
In a preferred embodiment of the present invention, a cobalt or copper salt, for example, cobalt naphthenate, is added along with the aforementioned adhesion promoting compounds to further improve adhesion. While cobalt naphthenate is known to improve metal adhesion of elastomeric stocks, no mention has ever been made of its use in fabric adhesion, by itself or in conjunction with other compounds.